EU VAT Solutions
US Sales Tax

Sales Tax compliance for all 50 states.

Economic nexus analysis, state registrations, marketplace facilitator law tracking, monthly filings and audit defence. From the Wayfair decision to the present-day marketplace-collection regime, CiDATax navigates the US sales tax landscape on your behalf.

The post-Wayfair landscape.

The 2018 Supreme Court decision in South Dakota v. Wayfair, Inc. abolished the physical-presence requirement for state sales tax obligations. Every US state now applies an economic nexus threshold, typically $100,000 in annual sales or 200 transactions, above which non-resident sellers must register and remit sales tax.

Thresholds, filing frequencies, taxability rules and marketplace-facilitator carve-outs all vary by state. The compliance cost of getting it wrong includes lookback assessments, statutory interest and penalties that can exceed the original tax due.

Economic nexus framework per South Dakota v. Wayfair, Inc., 585 U.S. _ (2018)

What we handle.

  • Economic nexus analysis across all 50 states + DC
  • Sales tax registration (state-by-state)
  • Marketplace Facilitator law tracking and reconciliation
  • Monthly, quarterly or annual filings per state cadence
  • Taxability classification for product catalogues
  • Sales tax permit renewals and surety bonds where required
  • Voluntary disclosure agreements (VDAs) for historic exposure
  • Audit defence at state revenue departments
  • Reverse audits to identify refund opportunities
When you trigger nexus

The four nexus triggers that catch sellers.

Economic Nexus

Sales-volume threshold

Most states: $100,000 annual sales or 200 transactions. California & Texas: $500,000. Kansas: any sales. Resets every calendar year. Crossing it once registers you indefinitely.

Physical Nexus

FBA inventory in-state

Holding inventory in an Amazon FBA warehouse establishes physical nexus. With 25+ FBA fulfilment centres across the US, Amazon sellers often have nexus they don't know about.

Click-through

Affiliate referrals

Some states (notably New York, California, Illinois) maintain click-through nexus rules where in-state affiliates paid on a commission basis create nexus for the principal seller.

Marketplace facilitator laws

Amazon collects, but you still file.

The marketplace facilitator reality.

Every US state now has a marketplace facilitator law making Amazon, eBay, Walmart and similar platforms responsible for collecting and remitting sales tax on third-party sales. This sounds like relief for sellers. It is not.

You still need to register in any state where you exceed economic nexus thresholds. You still need to file regular returns. You report marketplace-collected sales as exempt and remit tax only on direct (DTC) channel sales.

Misreporting marketplace-facilitated sales (claiming them as taxable when they were collected by Amazon, or vice versa) is a common cause of state audit triggers.

State-by-state complexity.

Each state runs its own rules on taxability of digital goods, SaaS, clothing, food, and dozens of niche categories. New York taxes clothing under $110 as exempt; Pennsylvania exempts most clothing entirely; California taxes most clothing in full.

CiDATax maintains a continuously updated taxability matrix for client SKUs across all jurisdictions where you have nexus. We re-classify when state rules change, which they do constantly.

Audit defence is included in our retainer for the duration of the engagement.

Ready to move forward?

Book a senior-led discovery call. We will scope your situation, set clear written terms, and put you on a defined timeline.